Funny enough, that's probably the worst way to convince engineers due to the belief that is rooted in this field which is both rockstar qualities and a false sense of security due to companies (so far) overpaying to reduce talent pools. So bringing up support staff and sales usually results in the mindset that they should just switch fields.

Instead talk about sports unions, like the NFL Player Association, and that usually gets them re-evaluating all they've been previously understanding about unions.